Violina R. Angelova, Agricultural University, Dept. of Chemistry, Mendeleev street 12, Plovdiv, 4000, Bulgaria, Tel: 359 32 642 242, Fax: 359 32 635920, Email violina@au-plovdiv.bg
Krasimir I. Ivanov, Agricultural University, Dept. of Chemistry, Mendeleev street 12, Plovdiv, 4000, Bulgaria, Tel: 359 32 642 240, Fax: 359 32 635920, Email kivanov@au-plovdiv.bg
Stefan V. Krustev, Agricultural University, Dept. of Chemistry, Mendeleev street 12, Plovdiv, 4000, Bulgaria, Tel: 359 32 642 269, Fax: 359 32 635920, Email krust@au-plovdiv.bg

Chemical immobilization is a promising technique for decrease of the mobility of the contaminants in ecosystems, in case of which chemical substances are added to the contaminated soils, for the purpose of reduction of the solubility and phytoaccessibility of metals, by means of absorption and/or sedimentation. The soil additives, used in phytostabilization, have to deactivate the metals quickly, to have a prolonged action, to be cheap and to be easily added to the soil. In a significant degree, some of the phosphorus-containing substances meet these conditions, among which are a certain part of the phosphate fertilizers, widely used in practice. The examinations in this respect are, however, episodical, while the results are often contradictory and they do not give a definite answer to the raised questions. This directed us to the conduction of a systematic examination having several basic tasks: (i) to determine the impact of some phosphate fertilizers on the quantity of the phytoaccessible forms of Pb, Zn and Cd, (ii) to compare the relative effectiveness of the selected additives on the accumulation of heavy metals in plants and (iii) to estimate the effect of the introduction of additives on the phytostabilization of contaminated soils. The obtained results show that the materials, containing P, examined by us, are effective in respect of the immobilization of heavy metals and they may be used in the growing of Triticale on moderately contaminated soils. One should have in mind that in the cases of soil contamination with Pb only, the superphosphate is more effective, while in case of combined contamination, it should be applied very carefully, because it leads to increase of Zn and Cd content in the epigeal parts of plants. In this case the application of KH2PO4 is more appropriate, because it is effective in respect to the three elements. The effect of the application of phosphorous-containing additives on the phytostabilization of soils, contaminated by heavy metals is compared to the effect of some organic fertilizers and sapropel (sediments on sea bed).

Stabilization and Removal of Arsenic and Other Metals from Groundwater Using EHC-M

Fayaz Lakhwala, Adventus Group, 1435 Morris Ave., Union, NJ 07083, Email: fayaz.lakhwala@adventusgroup.com
Joanna Moreno, Adventus Group, 11560 Penney Road, Conifer, CO 80433, Email: joanna.moreno@adventusgroup.com
Jim Mueller, Adventus Group,  2871  W. Forest Road, Suite 2, Freeport, IL 61032, Email: Jim.mueller@adventusgroup.com
Josephine Molin, Adventus Group, 2871  W. Forest Road, Suite 2, Freeport, IL 61032, Email: Josephine.molin@adventusgroup.com
David Hill, Adventus Group, 1345 Fewster Drive, Mississauga, Ontario, Canada L4W 2A51, Email: David.Hill@adventugroup.com
Eva Dmitrovic, Adventus Group,1345 Fewster Drive, Mississauga, Ontario, Canada L4W 2A51, Email: Eva.dmitrovic@adventusgroup.com
Andrzej Przepiora, Adventus Group, 745 Bridge St. W., Suite 7 , Waterloo, Ontario, Canada N2V 2G6, Email: Andrzej.przepiora@adventusgroup.com

EHC-M™ is a specially formulated version of controlled-release, integrated carbon and zero valent iron (ZVI) technology for in situ chemical reduction. EHC-M encourages the precipitation and adsorption of dissolved metals such as chromium, lead, arsenic, zinc and mercury, to limit their movement downstream of a treatment zone. Arsenic in ground water is largely the result of minerals dissolving from weathered rocks and soils. Arsenic is naturally occurring in the environment and is present in groundwater at concentrations ranging from 1 to >50 micrograms per liter (ug/L).

The primary mechanism of removal entails physical precipitation with iron and other inorganic compounds. For arsenic, this involves primarily the reduction of sulfate to form arsenopyrite. Given that the removal mechanisms are precipitation and adsorption, the metals are transferred from the aqueous phase to a solid phase.

EHC-M has been shown to rapidly reduce the concentration of dissolved arsenic in groundwater from >1,000 to <10 ug/L. Under continuous-flow laboratory conditions, removal efficiencies exceeding 98% were achieved.  After a period of loading the column with arsenic, a series of influent groundwater conditions were introduced into the column to demonstrate the ability of EHC-M to retain the arsenic despite conditions that could in theory reverse the process. Arsenic removal using EHC-M technology has been shown to be non-reversible by change in Eh or pH.  The total length of the study is 950 days, or 2.6 years, and counting. Data from these tests will be presented along with field application data and field implementation methods.

Data from tests to remove and stabilize chromium will also be presented.

Recent Record of Mercury in Precipitation in Central Virginia

Amy Friedlander, George Mushrush and Douglas Mose, Chemistry Department and Center for Basic and Applied Science, George Mason University, Fairfax, VA 22030, Tel:  703-993-1068, Fax:  703-273-2282

Since 2002, weekly measurements of mercury in rain and snow have been gathered in central Virginia , as part of the National Atmospheric Deposition Program (http://nadp.sws.uiuc.edu/mdn/). The major sources of mercury in the atmosphere are coal-fired electrical power plants. The collaboration between our central Virginia deposition site and the other mercury deposition sites across North America documents weekly deposition patterns. These can be used to determine situations in which the mercury in precititation is excessive. Such information can be used to modify power plant emission regulations. The average mercury depositions in central Virginia were about 7.5 ng/L, with higher concentrations occurring mainly in the spring and summer. The weekly mercury concentrations were greater in rainstorms following weeks without rain (and less during weeks of frequent rain). Unusually high concentrations occurred just prior to the passage of Hurricane Isabel in September of 2003, and unusually low concentrations just after the passage. Taken together with deposition patterns of other stations in the national network, the patterns of mercury concentrations do not serve to identify any of the power station sites known to emit mercury. Instead, the source of mercury in rain and snow in central Virginia is a global "mercury pool"  that is mixed and transported over long distances for weeks or months before it is deposited.

Remediation of Mercury Impacts to a Public Water Supply System

George D. Naslas, P.G., LSP, Weston & Sampson Engineers, Inc., 5 Centennial Drive, Peabody, MA 01960, Tel: 978-532-1900 ext. 2279, Email: naslasg@wseinc.com
Paul Uzgiris, P.E., Weston & Sampson Engineers, Inc., 5 Centennial Drive, Peabody, MA 01960, Tel: 978-532-1900 ext. 2254, Email: uzgirisp@wseinc.com
James Fair, P.E., Weston & Sampson Engineers, Inc., 5 Centennial Drive, Peabody, MA 01960, Tel: 978-532-1900 ext. 2234, Email: fairj@wseinc.com

A release of mercury at a municipal water well pump station building resulted in measurable concentrations of mercury in the water supply system, as well as in the concrete floor of the pump station building, in surrounding soil and mercury vapor in air in the building workspace.  The well, one of only two water supply wells for the community was immediately shut down.  Following an initial response to the spill, an approach to remediate all media including was developed, which not only provided technical challenges but also required the coordination between four departments of the Massachusetts Department of Environmental Protection (DEP).   

Initial response actions included the disconnection of the well from the system and excavation of impacted soil.  The problem was to rapidly evaluate if the mercury was present further down the distribution system and to evaluate all impacted media, including how deep mercury was released in soil, whether groundwater was impacted and how much of the concrete floor had absorbed mercury, which subsequently was de-gassing into the workspace.  To further complicate matters portions of the water main were asbestos pipe, requiring additional regulatory oversight.

Response activities performed include: physical recovery of spilled mercury, removal of impacted piping and equipment, decontamination of mercury-impacted surfaces in the building, basement ventilation, excavation and off-Site disposal of mercury-impacted soil, installation of three soil borings/shallow groundwater monitoring wells, and collection of air, soil, and groundwater samples for laboratory analysis.  The pipe was sampled at selected locations and no mercury was detected after a junction T-box located approximately 150-feet from the well.  The pump station was washed down using HG-X to remove potential off-gas sources of mercury.  The response actions resulted in regulatory closure and reconnection of this important water supply. 

Cadmium: A Sufficient or Holistic Approach towards Risk Assessment and Regulation within the Danish Landscape!

Billa Cyprian Nkem,  (TEKSAM), Building 11.2, Roskilde University, Box 260, 4000 Roskilde, Denmark, Tel:+45-4674 2120 Fax:+45-4674 3041, Email: bcn@ruc.dk
Srikanth Vangapandu, (TEKSAM), Building 11.2, Roskilde University, Box 260, 4000 Roskilde, Denmark, Tel:+45-4674 2120 Fax:+45-4674 3041, Email: srva@ruc.dk 
Sreedhar Reddy Javaji, (TEKSAM), Building 11.2, Roskilde University, Box 260, 4000 Roskilde, Denmark, Tel:+45-4674 2120 Fax:+45-4674 3041, Email:  sreddyj@ruc.dk

Cadmium, belonging to the group of heavy metals, is an environmental toxicant which is non essential to humans and living organisms but however implicated in many manufacturing processes. Over the course of the past years, there have been considerable efforts through established regulatory and risk reduction mechanisms in Denmark , to curb the spread, exposure and consequently toxic effects of this contaminant onto man and the entire ecosystem. However, some environmental exposure effects still abound. The soil remains to be the final recipient of all deposition pathways from anthropogenic parameters. Deposition on agricultural land(soil) in Denmark remains to be the most indirect pathway by which the general population becomes exposed as it is easily being absorbed by food crops largely via the use of phosphate fertilizers. This project aimed at identifying the various channels and parameters by which cadmium gets onto the Danish farmland as well as suggesting further risk reduction measures beyond what is actually in place. The application of phosphate fertilizers, sewage sludge and atmospheric deposition, were all identified as the most likely pathways by which cadmium additionally accumulates into farmland. In order to reduce further soil deposition, the project sought to recommend a general overhaul, of cadmium life cycle from the extraction to waste disposal phases, through the adoption environmentally friendlier innovative processes. This must demand firm commitment from all different relevant stakeholders both nationally and regionally whereby existing regulations be rigorously enforced as well as the establishment of new ones. All these would guarantee us a precautionary approach in a bid to keep levels and hence the resulting adverse effects, as low as possible.

Demonstration Project: Immobilization of Lead in Soil and Groundwater using Apatite II™

David Morin, Ph.D, TechnoRem Inc., 2345, Michelin, bureau 220, Laval, Québec H7L 5B9, Tel:  450-681-4749, Fax: 450-681-4581
Annie Morin, Eng., M.Sc., TechnoRem Inc., 2345, Michelin, bureau 220, Laval, Québec H7L 5B9, Tel:  450-681-4749, Fax: 450-681-4581, Email: annie.morin@technorem.com
Caroline Scalzo, Eng., M.Sc.A, TechnoRem Inc., 2345, Michelin, bureau 220, Laval, Québec, H7L 5B9, Tel: 450-681-4749, Fax: 450-681-4581
Adriana Peisajovich, Eng. , Ph.D, Environmental Affairs, Transport Canada , Regional Office Government of Canada , Dorval, Québec, Canada H4Y 1G7, Tel: 514-633-3956, Fax: 514-633-3250  
Judith Wright, Ph.D., President, PIMS NW, Inc., 403 West Riverside Drive, Carlsbad, NM, 88220-5263 USA, Tel: 505-628-0916, Fax: 505-628-0915, Email: judith@pimsnw.com

The main purpose of this project is to reduce dissolved lead concentrations in groundwater at an airport site to a level below the standard for drinking water (10 µg/L) by the application of a new phosphate medium called Apatite II™. 

Laboratory testing was conducted on soil and groundwater collected from inside the impacted area on the site.  Column tests confirmed that Apatite II has good potential for binding lead (Pb).  After water comes in contact with the Apatite II, slightly elevated concentrations of phosphorus (1.4 to 4.0 mg/L) seem to quickly resorb downstream of the reactive zone probably as a result of Pb and phosphate heterogeneous nucleation and precipitation as pyromorphite.

During the environmental characterization, lead concentrations in the groundwater reached 120 µg/L.  At that time, the impacted area extended 350 m² in the surface aquifer and approximately 275 m² in the bedrock aquifer. 

MODFLOW and MT3D models were used to simulate groundwater behaviour and lead transport beneath the site before and after the emplacement of the reactive barrier in the fall of 2004.  Work included excavation of the soil to be treated, mixing of the soil with Apatite II, backfilling and paving of the excavated area.

Groundwater monitoring shows that the reactive barrier has stabilized and reduced the lead contamination by one order of magnitude and to below the drinking water standard (10 µg/L) in some monitoring wells.  The reaction time was longer than expected, probably because of the low groundwater temperature and absence of surface infiltration.  Monitoring is still ongoing.

The use of Apatite II is a promising technology because the material is easy to apply and requires no treatment or maintenance infrastructure that limits the use of a site.   

In Situ Stabilization of Zinc in Soil and Groundwater 

Bernd W. Rehm, ReSolution Partners, LLC, P.O. Box 44181, Madison, WI 53744-4181, Tel: 608-669-1249, Fax: 608-938-4500
Robert Kondelin, Environmental Alliance, Inc., 1812 Newport Gap Pike, Wilmington, DE 19808, Tel: 302-995-7544, Fax: 302-995-0941
Steve Markesic, Redox Technology, LLC, 1441 Branding Lane, Suite 100, Downers Grove, IL 60515, Tel: 630-515-1810, Fax: 630-960-0660  

A 21-acre parcel in the Mid-Atlantic United States hosted several industrial operations from 1907 to 1982.  Groundwater is present at 5 feet bgs in heterogeneous alluvium and saprolite.  Flow rates are on the order of 100 feet per year.  Groundwater at a pH of 5 SU and containing as much as 30 mg/L of zinc discharges to a small stream on one edge of the facility.  The site surface was remediated and redeveloped into an apartment complex.  Groundwater remediation to a goal of 2.0 mg/L zinc was deferred until after the apartment complex was built.  In situ stabilization technologies that could be applied with minimal interference with site use were evaluated in bench-scale and in-field pilot tests.  A slurry reagent that could be injected below the developed site was identified.  The bench scale testing using site soil and groundwater samples found a 4 weight percent (wt. %) slurry dose increased pH to 10 SU and reduced zinc concentrations from 14.7 to 0.013 mg/L.  The proposed remedial design took the form of a reactive zone at the edge of the facility, which required an evaluation of the long-term stability of an injected reactive zone.  Multiple extractions found an extractant pH of 8.5 SU and zinc concentration of 0.088 mg/L of zinc following about 1,200 aquifer pore volumes of leaching, equivalent to 400 years at the site groundwater flow rate.  Pilot testing was completed with direct-push injection methods.  Approximately 7.3 tons of reagent slurried in 4,205 gallons of water was injected at six points.  Temporary well samples within the injection zone had post-injection zinc concentrations of <0.020 mg/L.  A monitoring well downgradient of the injection zone yielded 21 mg/L of zinc prior to the injection.  Three months later the zinc concentration at the downgradient well was 5.4 mg/L.  Approval for full-scale implementation was received and performed in August 2007.

Kinetics and Isotherm Equilibrium Adsorption of Copper(II) Ions onto Chemically Modified Barley Waste

Li-Jyur Tsai, Department of Environmental Engineering and Science, Chia-Nan University of Pharmacy and Science, Tainan 717, Taiwan, Tel: 886 6-2660254, Fax: 886 6-3662668, Email: lijyur@ms22.hinet.net
Kuang-Chung Yu, Department of Environmental Engineering and Sciemce, Chia-Nan University of Pharmacy and Science, Tainan 717, Taiwan, Tel: 886 6-2660254, Fax: (886) 6-3662668, Email: kuchuyu@ksts.seed.net.tw
Shien-Tsong Ho, Department of Industrial Safety and Hygiene, Chia-Nan University of Pharmacy and Science, Tainan 717, Taiwan, Tel: 886 6-2660254, Fax: 886 6-3662668, Email: hohc@ms28.hinet.net

Barley waste of 30-40 mesh size was chemically modified by combinations of treatments, consisting of either 1% thiourea or no thiourea cross-linkage treatment followed by modification with acidified formaldehyde, 0.6 M citric acid, or sodium thiosulfate to improve the physical and chemical adsorption capacity of copper(II) ions. Adsorption capacity of copper(II) ions from aqueous solution onto chemically modified barley waste adsorbents have been carried out with the variation of pH, temperature, and copper(II) ions concentrations at batch experiment. Maximum adsorption capacities of copper(II) ions for all of the adsorbents had found at around pH 4.5～6.5. The Langmuir, Freundlich and Dubinin-Radushkevich(D-R) adsorption isotherm equilibrium models were used to describe the adsorption behavior. The maximum adsorption capacity (Qmax) of copper(II) ions predicted with Langmuir equation were 0.36 mM/g for citric acid modified barley adsorbent, 0.35 mM/g for thiourea modified barley adsorbent, 0.34 mM/g for barley adsorbents modified with thiourea and sodium thiosulfate and 0.33 mM/g for sodium thiosulfate modified barley adsorbent, when 0.25g adsorbent mix with an initial 100mL 28.5mg/L copper(II) ions at 30 ^oC and pH 5.5. Three adsorption kinetic models including pseudo-first-order rate, pseudo-second-order rate, and intraparticle diffusion equations were used to discuss the adsorption mechanism of copper(II) ions and barley adsorbents. The experimental data of copper(II) ions which adsorbed onto modified barley adsorbents fitted excellently the pseudo-second-order rate model and gave the best correlation coefficients (r2＝0.94～1.0). It showed that chemical adsorption was the basic mechanism for this process.

The positive enthalpy change (ΔH0 > 0) for the isotherm adsorption process from 15 to 70 15 to 70 ^oC was found, indicating that the adsorption of copper(II) ion was endothermic process and the adsorption capacity increase with increasing temperature. The negative Gibbs free energy change (ΔG0<0) showed that the adsorption process was spontaneous. The positive entropy change (ΔS0>0) suggested that the adsorption of copper(II) ion onto chemically modified barley waste increased randomness between adsorbent solid surface and copper(II) ion in the solution. Those results showed that low economical barley waste could be chemically modified into adsorbents for the removal of heavy metals from aqueous solutions.

Estimation of Pollution Level in Soil from Mining Region

Vasile Viman, Prof Dr., Gheorghe Vatca, Assoc. Prof Dr., Anca Mihali-Cozmuta, Assoc. Prof Dr., Leonard Mihali Cozmuta, Lecturer Dr., Vasile Anitas, Ing., North University of Baia Mare, 62/A Victor Babes St., Baia Mare, Romania, Tel: 40-262-276-059, Fax: 40-262-275-368, Email: v_viman@hotmail.com

The researched region is characterized by the following mining activities: ores extractions which contain heavy metals (Pb, Cu, and Zn), ores enrichment in useful components by flotation process, processing of mining concentrates by pyrometallurgical method.

These activities contribute to soil pollution through the following:

• Sterile residues from mines neighborhood
• Mining waters which contain heavy metals and have a strong acid pH 
• Waste waters from flotation plants which contain heavy metals and used cyanides as flotation reactive  
• Suspended and sedimentable powders eliminated by metallurgical plants.

The pollutant powders from above mentioned sources can reach the soil carried by wind or rain. Also, waste waters can reach decantation ponds through accidental leaks.

To estimate the level of soil pollution, collection networks of samples were established on different direction and depths from the pollution sources, coordinates being established with a GPS device having as a goal a pollution map drawing.

Dried and burned collected samples are passed through solution with mixed acids and than analyzed by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) method to determinate the concentration of Pb, Cu, Zn. The experimental results show concentrations from hundreds to thousands of ppm., overreaching in most cases the maximum admitted concentration level.

Soil pollution from this region affects crops in quantity and quality with negative effects on people’s health.  

Application of Calcium Oxyphosphate and Ferrous Sulphate for Pb and As Stabilization 

Anthimos Xenidis, Lab. of Metallurgy, National Technical University of Athens, GR 157 80 Zografos, Athens, Greece  

The potential for chemical immobilization of Pb and As in heavily contaminated soil from Lavrion , Greece was investigated. Calcium oxyphosphate dehydrate (Ca₂(H₂PO₄)^.2H₂O) and/or ferrous sulphate (FeSO₄) solution were used as stabilizing agents. Calcium oxyphosphate was added to contaminated soil at PO₄ to Pb molar ratios equal to 0, 0.5, 1, 1.5 and 2.5, whereas ferrous sulphate was added at Fe to As molar ratios equal to 0, 2.5, 5, 10 and 20. Stabilization was evaluated by applying both chemical extraction tests and vegetation tests using dwarf beans as inicators. In agreement with previous studies, it was indicated that calcium oxyphosphate addition to contaminated soil significantly decreased Pb leachability, whereas it leads to a significant mobilization of As. In order to address this adverse effect iron was added in the form of ferrous iron sulphate solution. It was found that the addition of both calcium oxyphosphate and ferrous sulphate proved to be an effective method for immobilizing both contaminants in soil. The addition of at least 1.5 M/M phosphates and 10 M/M iron sulphate to the soil sample tested significantly reduced the dissolved levels of Pb and As in the water extracts to values in compliance with the EU drinking water standards. Biological tests using Phaseolus Vulgaris Starazagorski indicated that the treatment did not result in any significant change on plants growth and metals uptake.

Top